2. The influence of the number of spindle revolutions on temperature
Figure 4 Relationship between spindle speed and surface temperature of diamond bit
Figure 5 Relationship between spindle speed and surface temperature of diamond bit
Fig. 4 is a graph showing the relationship between the surface temperature of the diamond bit and the drilling time when the marble is drilled at a feed speed of 15 mm/min and a spindle speed of 300 rpm, 400 rpm, and 500 rpm, respectively. Overall, the temperature rises linearly with time. In addition, it can be seen from Fig. 5 that the temperature increases as the spindle speed increases. However, the temperature rise is not obvious. When the number of spindle revolutions reaches 500r/min, the maximum temperature is 143 °C. The spindle speed increases. The number of rubbing of the diamond particles and the stone in the unit time increases, and the contact time is long, thereby causing the surface temperature to increase.
3. The effect of stone properties on surface temperature
Figure 5 shows the spindle speed of 300 rpm and the feed rate of 15 mm/min. Processing the average surface temperature of different stone diamond drill bits. It can be seen from Fig. 5 that the diamond surface temperature is the largest when drilling granite, reaching l50 °C, while the surface temperature is the lowest when processing sandstone is 30 °C; the temperature when processing marble is 70 °C. According to the properties of stone, the density of granite is 2.5-2.7kg/cm3, the compressive strength is 120-250MPa, the density of marble is 2.5-2.7kg/cm3, the compressive strength is 47-120MPa, and the density of sandstone is 2.2 ~ 2.5kg / cm3, compressive strength 47 ~ 120MPa. The density of the three types of stone is basically the same, but the compressive strength of granite is much greater than that of marble and sandstone, almost twice that of marble and sandstone. The strength of the stone increases, the cutting force increases, and the diamond tool wears severely, resulting in an increase in the surface temperature of the diamond bit. It can be seen from Fig. 5 that the surface temperature of the diamond cutter when processing granite is twice that of the processed marble and five times that of the sandstone. It can be seen from the processing experiment that when the granite is dry-cut, the surface temperature of the diamond cutter rises rapidly, and the temperature is high, causing the diamond cutter head to fall off. The thermal conductivity of granite is 3.49W/mK, and the thermal conductivity of copper is 370.49W/mK. It can be seen that most of the heat is transferred by the diamond drill bit, which leads to a sharp increase in the surface temperature of the diamond drill bit. Diamond wear is severe.
Figure 6 stone type and diamond bit surface temperature
in conclusion
When using a diamond bit to process stone, the machining parameters such as spindle speed and drilling speed have a great influence on the tool surface temperature. The tool surface temperature increases as the spindle speed and feed rate increase. The surface temperature of the diamond bit increases as the drilling time increases, and is proportional to the drilling time.
The performance of the stone has a great influence on the surface temperature of the diamond bit. When drilling granite under the same conditions, the surface temperature of the drill bit is twice that of marble and five times that of sandstone. Coolant should be used for dry drilling to prevent diamond bit wear. Brazing or laser welding should be used for sintered diamond. It can ensure that the weld is resistant to high temperature and the diamond cutter head will not fall off earlier.
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